1. Technical Field
The present disclosure generally relates to apparatuses and methods for evaluating formations traversed by a well borehole.
2. Background Information
In the oil and gas industry, formation testing tools have been used for monitoring formation pressures along a well borehole, obtaining formation fluid samples from the borehole and predicting performance of reservoirs around the borehole. Such formation testing tools typically contain an elongated body having an elastomeric packer and/or pad that is sealingly urged against a zone of interest in the borehole to collect formation fluid samples in fluid receiving chambers placed in the tool.
Downhole multi-tester instruments have been developed with extensible sampling probes for engaging the borehole wall at the formation of interest for withdrawing fluid samples from the formation and for measuring pressure. In downhole instruments of this nature an internal pump or piston may be used after engaging the borehole wall to reduce pressure at the instrument formation interface causing fluid to flow from the formation into the instrument.